Design and preparation of pyrrole-based spin-polarized donors

As a fundamental building block of a conductive magnetic macromolecule, a series of pyrrole derivatives carrying a nitronyl nitroxide (NN) group was prepared. Some of these derivatives afforded ground-state triplet diradical cations upon one-electron oxidation, and the difference in the spin multiplicities of the singly oxidized pyrrolylNNs was rationalized on the basis of a perturbational molecular orbital method. The electronic interaction between the pyrrole and the nitronyl nitroxide parts was also confirmed by cyclic voltammetry and UV-Vis absorption spectroscopy. In spite of the vacancy of the 2 and 5 positions of the pyrrole ring, electrochemical polymerization of these derivatives was not observed, except for an extended alpha-thienyl derivative.